Hydration Time Research Articles

Synthesis and Characterization of Calcium Sulfoaluminate Hydrates-Ettringite (AFt) and Monosulfate (AFm).

The goal of the presented work was to find the most favorable conditions for the synthesis and stabilization of chemically pure ettringite and monosulfate. The reaction was carried out by mixing pure tricalcium aluminate (C3A) and gypsum (CS¯H2) in an excess amount of water. The impact of hydration time (2-7 days), C3A:CS¯ molar ratio (1:1-1:3) and water vapor pressure of the selected drying agents (anhydrite-III and supersaturated CaCl2 solution) on the phase composition of the products was evaluated. After 7 days of hydration, either ettringite or monosulfate was obtained as the main product, depending on the C3A:CS¯ molar ratio. The synthesis carried out at a C3A:CS¯ molar ratio of 1:3 produced pure ettringite. In the case of the sample characterized by the ratio of 1:1 (typical of monosulfate), a considerable portion of ettringite (27.9%) was present in the final products along the AFm phase. Therefore, a different synthesis method has to be selected in order to obtain pure monosulfate. The results showed that thermal analysis, X-ray diffractometry and FTIR spectroscopy can be used to distinguish the characteristic features of ettringite and monosulfate.

Impact of TiO2 powder type on hydration and photocatalytic NOx degradation in cement paste

This study was aimed at developing novel functional construction materials with NOx removal capabilities using TiO2 powder. To this end, the effects of the chemical composition of TiO2 powder on the hydration process and the mechanical properties of cement were investigated. The hydration characteristics of the cement were assessed by analyzing the setting time and heat of hydration, while the mechanical properties were evaluated by measuring compressive strength at different curing ages. Additionally, the NOx degradation performance was examined. The results demonstrate that TiO2 powder accelerates the hydration of cement, enhancing the compressive strength during the early stages of hydration. Furthermore, the NOx degradation performance of mortar specimens was enhanced with the incorporation of TiO2 powder. However, the extent of these improvements varied significantly depending on the chemical composition of the TiO2 powder, with the composition ratio of anatase and rutile being particularly influential. When utilizing TiO2 powder to enhance the performance of construction materials or impart new functional properties, it is advisable to consider the composition of the TiO2 powder to ensure alignment with the intended performance improvement objectives.

Thermal and textural properties of extruded rice affect its cooking performances and the texture of the steamed extruded rice

Extruded rice has increasingly gained popularity in the market due to its convenience and acceptable texture. The objective of this study was to understand how the physicochemical, thermal, and textural properties of the extruded rice affected its cooking properties and texture of the cooked one. It was found that air trapped in the grains during extrusion reduced the transparency of extruded rice. More air trapped in the grains reduced the true density of the extruded rice, which in turn decreased the hardness of extruded rice. A looser internal structure of extruded rice grain, as indicated by the lower true density, resulted in a faster hydration and shorter optimum cooking time. Extruded rices showed two thermal-transition peaks, with peak 1 from 93.3 °C to 112.8 °C and peak 2 from 107.5 °C to 132.5 °C. The increased hardness of extruded rice led to increases in its thermal-transition temperatures, longer optimum steaming time, and decreases in its water absorption and cooking loss, which resulted in an increase in the hardness and a reduction in the adhesiveness of the steamed one. This study provides insights into the key factors determining the eating quality of extruded rice, which is beneficial for food scientists in developing premium extruded rice.

Hydration and Mechanical Properties of High-Volume Fly Ash Cement under Different Curing Temperatures.

This study aimed to investigate the effects of different curing temperatures on the hydration and mechanical properties of high-volume fly ash (HVFA) concrete. The key variables were curing temperature (13 °C, 23 °C, 43 °C) and fly ash (FA) content (0%, 35%, 55%). The hydration characteristics of HVFA cement were examined by evaluating the setting time and heat of hydration under different curing temperatures. The mechanical properties of HVFA concrete were analyzed by preparing concrete specimens at various curing temperatures and measuring the compressive strength at 7, 28, 56, and 91 days. The results indicated that concrete with high FA content was more sensitive to curing temperature compared to ordinary Portland cement.

Technological and multi‐sensory analysis approach to holistically understand the quality and consumer perception of gluten‐free breads with alternative flours

SummaryThe aim of this study was to characterise gluten‐free breads formulated with alternative flours through technological and sensory (ultra flash profiling, hedonic tests) properties, and to correlate both methodologies for holistically understanding how these variables affect the consumer preference and product quality. Gluten‐free breads formulated by replacing 20% with brown rice, lupine, millet, quinoa, sorghum, teff, buckwheat, rice bran and carob flours were evaluated. The dough hydration and fermentation times were optimised. The formulations presented differences in centesimal composition, specific volume, texture and colour. Significant correlations were established between fermentation time, specific volume, centesimal composition, texture (hardness, gumminess), alveolar structure (porosity, uniformity, cell density), colour (L*), sensory descriptors and overall acceptability. The ultra flash profiling test confirmed different sensory profiles, showing that some descriptors have a high impact in overall acceptability. Multiple factor analysis contributed to understand the interrelationships between technological and sensory properties, identifying the relevant technological parameters that affect the consumer preferences and the final product quality.

Early length changes and microscopic phase analysis of phosphorus hemihydrate gypsum fireproof mortar

Abstract Coating the surface of steel structures with phosphohemihydrate gypsum fireproof mortar can improve the fire resistance of steel structures. The hydration curve of phosphorus hemihydrate gypsum (PHG) showed a monotonic increasing trend, and the hydration time was about 1 day. In order to study the hydration process of phosphorus hemihydrate gypsum fireproof mortar, its length change in the early hardening stage was experimentally investigated. The results showed that compared with the hydration time of phosphohemihydrate gypsum, the duration of early length changes in phosphohemihydrate gypsum fireproof mortar was significantly prolonged to about 4 days, and four intervals were clearly observed during this process. Hydroxypropyl methyl cellulose (HPMC) as a water retaining agent, hydroxypropyl starch ether (HPS) as a thixotropic agent, and dispersed latex powder (LP) can all make the four intervals of length changes of fireproof mortar more significant. After adding HPMC, HPS, and LP, it can promote the formation of dihydrate gypsum mainly in fireproof mortar, but dihydrate gypsum crystals were more likely to grow along the [021] direction. The addition of additives can also effectively improve the pore structure of phosphogypsum fireproof mortar.

Lipid loss and compositional change during preparation of simple two-component liposomes

Liposomes are used as model membranes in many scientific fields. Various methods exist to prepare liposomes, but common procedures include thin-film hydration followed by extrusion, freeze-thaw, and/or sonication. These procedures can produce liposomes at specific concentrations and lipid compositions, and researchers often assume that the concentration and composition of their liposomes are similar or identical to what would be expected if no lipid loss occurred. However, lipid loss and concomitant biasing of lipid composition can in principle occur at any preparation step due to nonideal mixing, lipid-surface interactions, etc. Here, we report a straightforward HPLC-ELSD method to quantify the lipid concentration and composition of liposomes and apply that method to study the preparation of simple cholesterol/POPC liposomes. We examine common liposome preparation steps, including vortexing during resuspension, lipid film hydration, extrusion, freeze-thaw, and sonication. We found that the resuspension step can play an outsized role in determining the lipid loss (up to ∼50% under seemingly rigorous procedures). The extrusion step yielded smaller lipid losses (∼10–20%). Freeze-thaw and sonication could both be employed to improve lipid yields. Hydration times up to 60 min and increasing cholesterol concentrations up to 50 mol % had little influence on lipid recovery. Fortunately, even conditions with large lipid loss did not substantially influence the target membrane composition, as long as the lipid mixture was below the cholesterol solubility limit. From our results, we identify best practices for producing maximum levels of lipid recovery and minimal changes to lipid composition during liposome preparation for cholesterol/POPC liposomes.

Study on the influence of nano-silica substitution of reactive Si on the properties and hydration process of alkali-activated cementitious materials paste

Nano-silica (NS) is one of the most commonly used nanomaterials in alkali-activated materials (AAMs). Differing from other inactive nanoparticles, as an active Si source, the pozzolanic activity of NS has a significant effect on the hydration reaction and properties of alkali-activated materials. In this study, activated Si in the activator was replaced by NS to prepare alkali-activated slag/fly ash cementitious materials. The effects of different dispersion methods (dry-mix (MD), water dispersion (WD), and activator dispersion (AD)) of NS on the fluidity, rheological properties, and setting time of fresh pastes were investigated. Effects of NS and reactive Si in the activator on the hydration process of alkali-activated slag/fly ash paste were investigated using isothermal calorimetry and the Krstulović-Dabić hydration model. ICP-OES was utilized to study the changing behavior of the composition of the fresh paste pore solution during the hydration reaction. The results show that ions in the pore solution change continuously with the hydration time and eventually stabilize. The stabilized pore solution is mainly composed of OH- and Na+. Different NS dispersion methods have significant effects on paste workability, rheology, and setting time. Activator dispersion can elevate the content of active Si in the activator, causing changes in the hydration process of the paste, especially for the initial hydration period. NS has the most significant effect on the hydration process due to its pozzolanic activity compared to nucleation and filling effects. The Krstulovic-Dabic model can roughly simulate the hydration kinetics possessed of alkali-activated NS/slag/fly ash after entering the accelerated period.

Femtosecond laser direct nanolithography of perovskite hydration for temporally programmable holograms

Modern nanofabrication technologies have propelled significant advancement of high-resolution and optically thin holograms. However, it remains a long-standing challenge to tune the complex hologram patterns at the nanoscale for temporal light field control. Here, we report femtosecond laser direct lithography of perovskites with nanoscale feature size and pixel-level temporal dynamics control for temporally programmable holograms. Specifically, under tightly focused laser irradiation, the organic molecules of layered perovskites (PEA)2PbI4 can be exfoliated with nanometric thickness precision and subwavelength lateral size. This creates inorganic lead halide capping nanostructures that retard perovskite hydration, enabling tunable hydration time constant. Leveraging advanced inverse design methods, temporal holograms in which multiple independent images are multiplexed with low cross talk are demonstrated. Furthermore, cascaded holograms are constructed to form temporally holographic neural networks with programmable optical inference functionality. Our work opens up new opportunities for tunable photonic devices with broad impacts on holography display and storage, high-dimensional optical encryption and artificial intelligence.

Bio-Inspired Double-Layered Hydrogel Robot with Fast Response via Thermo-Responsive Effect.

Bio-inspired hydrogel robots have become promising due to their advantage of the interaction safety and comfort between robots and humans, while current hydrogel robots mainly focus on underwater movement due to the hydration-dehydration process of thermo-responsive hydrogels, which greatly limits their practical applications. To expand the motion of the thermo-responsive hydrogel robot to the ground, we constructed a hydrogel robot inspired by a caterpillar, which has an anisotropic double-layered structure by the interfacial diffusion polymerization method. Adding PVA and SA to PNIPAm will cause different conformation transitions. Therefore, sticking the two layers of hydrogel together will form a double-layer anisotropic structure. The ultra-high hydrophilicity of PVA and SA significantly reduces the contact angle of the hydrogel from 53.1° to about 10° and reduces its hydration time. The responsive time for bending 30° of the hydrogel robot has been greatly reduced from 1 h to half an hour through the enhancement of photo-thermal conversion and thermal conductivity via the addition of Fe3O4 nanoparticles. As a result, the fabricated hydrogel robot can achieve a high moving speed of 54.5 mm·h-1 on the ground. Additionally, the fabricated hydrogel has excellent mechanical strength and can endure significant flexibility tests. This work may pave the road for the development of soft robots and expand their applications in industry.

Development of gluten-free and gum-free rice bread: influence of ingredients, hydration and processing time on bread quality

Gluten-free and gum-free breads were developed, with the focus on the impact of raw materials (rice grain or flour) and processing conditions (pre-hydration and mixing time). The evaluation of bread quality primarily involved after the measurement of specific volume (BV), alveolar area (AA), and crumb hardness both before and storage. BV varied within 1.99–2.97 ml/g for rice bread and 2.14–2.26 ml/g for flour bread, with control (containing xanthan gum) values of 2.65 and 3.11 ml/g for rice and flour bread, respectively. An increase in AA was observed (rice: 0.5–1.9 mm2 and flour: 0.76–2.0 mm2) compared to controls with gum (rice: 0.36 and flour: 1.41 mm2). Pre-hydration of ingredients and reduced mixing time improved bread quality: volume of bread from hydrated rice and 4 min of mixing time was comparable to that of gum control. Although the aging process, measured by hardness, was faster than in gum-containing bread, process conditions were identified that delayed aging. This information is essential and valuable for future research.

An annealing-free method for processing high-moisture iron-containing sludge of metallurgical production

The purpose of this study was to study the possibility of producing high-strength briquettes from high-moisture iron-containing slimes by hydration with quicklime (chemical dehydration) in combination with dolomite dust from a degusting system and carbon-containing pulverized materials and developing a drainless technology for the production of complex self-healing briquettes. The physicochemical conditions of the hydration process, temperature and time parameters of the process were studied, and the choice of active dehydrating materials significantly increased the degree of hydration of the composite system and their optimal ratios, and the period of the beginning and end of self-hardening were determined. The conditions of combining the processes of dehydration, and self-hardening with the processes of melding, when applying external pressure to a hardening mixture in a meld to obtain a coated material in the form of a briquette in one technological cycle are considered, which is one of the main provisions of the scientific novelty of the proposed method. Optimal conditions for the production of high-strength briquettes suitable for metallurgical production technologies, excluding the stages of thermal drying and firing, have been established, and a set of strength properties occurs in the air. The method allows obtaining a self-healing dipped material by introducing a carbon-containing reducing agent into a slurry-lime self-hardening mixture. Cheap waste pulverized limestone and dolomite roasting wastes are used as a dehydrating material, and pulverized carbonaceous materials (coke and coal screenings) are used as a reducing agent. Unlike well-known technical solutions, the proposed technology and the method incorporated in it eliminates the storage of iron-containing sludge in a sludge storage facility and allows you to organize a drainless scheme of non-annealing and the production of complex self-healing iron-containing material for the production of steel and rolled products. The technology will make it possible to organize production for the processing of high-moisture iron-containing sludge, pulverized calcium- and magnesium-containing and carbon-containing pulverized waste and also solves the problems of environmental pollution and land allocation for the storage of industrial waste.

Mix and measure II: joint high-energy laboratory powder diffraction and microtomography for cement hydration studies.

Portland cements (PCs) and cement blends are multiphase materials of different fineness, and quantitatively analysing their hydration pathways is very challenging. The dissolution (hydration) of the initial crystalline and amorphous phases must be determined, as well as the formation of labile (such as ettringite), reactive (such as portlandite) and amorphous (such as calcium silicate hydrate gel) components. The microstructural changes with hydration time must also be mapped out. To address this robustly and accurately, an innovative approach is being developed based on in situ measurements of pastes without any sample conditioning. Data are sequentially acquired by Mo Kα1 laboratory X-ray powder diffraction (LXRPD) and microtomography (µCT), where the same volume is scanned with time to reduce variability. Wide capillaries (2 mm in diameter) are key to avoid artefacts, e.g. self-desiccation, and to have excellent particle averaging. This methodology is tested in three cement paste samples: (i) a commercial PC 52.5 R, (ii) a blend of 80 wt% of this PC and 20 wt% quartz, to simulate an addition of supplementary cementitious materials, and (iii) a blend of 80 wt% PC and 20 wt% limestone, to simulate a limestone Portland cement. LXRPD data are acquired at 3 h and 1, 3, 7 and 28 days, and µCT data are collected at 12 h and 1, 3, 7 and 28 days. Later age data can also be easily acquired. In this methodology, the amounts of the crystalline phases are directly obtained from Rietveld analysis and the amorphous phase contents are obtained from mass-balance calculations. From the µCT study, and within the attained spatial resolution, three components (porosity, hydrated products and unhydrated cement particles) are determined. The analyses quantitatively demonstrate the filler effect of quartz and limestone in the hydration of alite and the calcium aluminate phases. Further hydration details are discussed.

Prediction of the heat of hydration of fly ash concrete by adiabatic temperature rise test and regression analysis

This paper deals with the proposal of a model that can predict heat of hydration of concrete containing fly ash and the adiabatic temperature rise test results that are the basis of the model. For the adiabatic temperature rise tests, total of twelve concrete mixtures were prepared with variables of the percentage of fly ash replacement and w/cm. The test results indicate that the replacement of fly ash significantly reduces the adiabatic temperature rise and delays the early hydration of fly-ash blended cements. Additionally, w/cm was found to influence not only the maximum adiabatic temperature rise but also the slope of the temperature rise. Therefore, a regression analysis was conducted to propose three parameters (hydration time parameter, hydration slope parameter, ultimate degree of hydration) for the heat of hydration model of concrete containing fly ash. The developed heat of hydration model was validated using test data. Models that did not consider w/cm, similar to those proposed by other researchers, failed to accurately predict the test results. However, the final model developed, which incorporates w/cm, accurately predicted the test results, as confirmed through this study.

Impact of Lime Saturation Factor on Alite-Ye'Elimite Cement Synthesis and Hydration.

Alite(C3S)-Ye'elimite(C4A3$) cement is a high cementitious material that incorporates a precise proportion of ye'elimite into the ordinary Portland cement. The synthesis and hydration behavior of Alite-Ye'elimite clinker with different lime saturation factors were investigated. The clinkers were synthesized using a secondary thermal treatment process, and their compositions were characterized. The hydrated pastes were analyzed for their hydration products, pore structure, mechanical strength, and microstructure. The clinkers and hydration products were characterized using XRD, TG-DSC, SEM, and MIP analysis. The results showed that the Alite-Ye'elimite cement clinker with a lime saturation factor (KH) of 0.93, prepared through secondary heat treatment, contained 64.88% C3S and 2.06% C4A3$. At this composition, the Alite-Ye'elimite cement clinker demonstrated the highest 28-day strength. The addition of SO3 to the clinkers decreased the content of tricalcium aluminate (C3A) and the ratio of Alite/Belite (C3S/C2S), resulting in a preference for belite formation. The pore structure of the hydrated pastes was also investigated, revealing a distribution of pore sizes ranging from 0.01 to 10 μm, with two peaks on each differential distribution curve corresponding to micron and sub-micron pores. The pore volume decreased from 0.22 ± 0.03 to 0.15 ± 0.18 cm3 g-1, and the main peak of pore distribution shifted towards smaller sizes with increasing hydration time.

Simulation analysis of microstructure development of tricalcium silicate using the needle model of calcium silicate hydrate

This study proposes a two-scale model for tricalcium silicate (C3S) hydration to examine the microstructure of hydrated C3S paste. The needle-like morphology of a calcium silicate hydrate (C-S-H) layer, as observed in many studies, was constructed using this model based on the assumption of C-S-H needles. The boundary nucleation and growth pattern of the C-S-H needles were illustrated, and the impingement among C-S-H needles and particles was considered. The pore size distribution was calculated using the rolling sphere method for the hydrated particle system and C-S-H layer. The simulation results were compared with existing experimental data, revealing consistency for the C3S paste with different hydration times. The shape and growth parameters of the C-S-H needles were studied to model their microstructure. The microstructure constructed using this model was found to be more reasonable and could provide a more accurate description of the C-S-H morphology.

Pore structure characteristics of artificial sand aggregate mortar

With the progressive depletion of natural sand, the substitution of natural sand with artificial sand as a construction aggregate has received significant attention. To analyzed the pore structure characteristics of artificial sand aggregate mortars, nuclear magnetic resonance (NMR) technology was utilized to analyze the distribution characteristics and dynamic changes of five types of aggregate gradation mortars, and fractal theory was employed for characterization. The study examined on the correlation between aggregate gradation and pore structure, fractal dimension, and assessed the connectivity of the pore structure. The results showed that: water-saturated samples were mainly composed of micropores and movable fluid pores after 28 days of hydration, while the micropores and clay-bound fluid pores dominated after 365 days of hydration. The formation of the pore structure in multi-aggregate-graded mortar is influenced by both the surface-to-volume ratio and aggregate packing density. At the same hydration time, lower porosity in water-saturated mortar results in increased non-homogeneity of the pore structure and a reduced permeability coefficient. Well-graded aggregate mortar has stronger resistance to hydraulic erosion, and the stronger the erosion effect of water will be with more developed pore structure.

Study on the mechanism of controlling the morphology of basic magnesium carbonate prepared under different hydration conditions

Basic magnesium carbonate is gaining prominence in flame retardant materials due to its excellent flame-retardant properties and clean decomposition products. This study investigates a hydration-carbonation method to address challenges related to the preparation, morphology control, and stability of magnesium basic carbonate. The impact of hydration conditions on the morphology of the carbonate was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicate that spherical magnesium basic carbonate with regular morphology and uniform particle size can be achieved at a hydration temperature of 50°C for 1.5 hours. However, extending the hydration time and increasing the temperature resulted in irregular morphologies. Molecular dynamics simulations using the CASTEP and Forcite modules of Materials Studio were employed to understand the influence of hydration-carbonation conditions on the carbonate's morphology. The simulations revealed that the (1 1 1) and (2 0 0) crystal faces of MgO, with higher surface energies, promote the formation of precursor magnesium hydroxide nuclei, leading to heterogeneous magnesium alkali carbonate at elevated temperatures. Prolonged hydration time resulted in fragmented carbonate structures. To control the morphology of magnesium alkali carbonate, it is essential to optimize hydration temperature and duration. The simulation results corroborate experimental findings, providing deeper insights into the liquid-gas-solid adsorption relationships during the carbonation process. This study offers valuable guidelines for the controlled synthesis of magnesium basic carbonate, enhancing its applicability in flame retardant materials.

Study of wellbore instability in shale formation considering the effect of hydration on strength weakening

Shale formations often contain a high proportion of clay minerals, which, upon contact with drilling fluid, undergo hydration expansion. This leads to wellbore instability, a problem that poses significant challenges globally. This study aims to investigate the variation of mechanical properties of shale with respect to hydration time. We employ an empirical model that relates shale strength parameters to the time of drilling through geological formations. Additionally, we consider both shear failure along the wellbore boundary and shear sliding along bedding planes in the analysis. We establish a predictive model for wellbore instability in shale formations. The model quantitatively analyzes the variation of wellbore collapse pressure with drilling time. The research findings indicate that, when the influence of bedding is considered, both the wellbore collapse pressure and the optimal well trajectory undergo significant changes, in addition, for some wellbore trajectories, the collapse pressure can increase by more than 30%. Therefore, it is essential to account for the influence of bedding in wellbore stability analysis in shale formations. As the bedding dip angle changes, both the numerical values and distribution range of wellbore collapse pressure and the optimal well trajectory change noticeably. Changes in bedding dip direction, however, do not affect the numerical values of collapse pressure but do influence the distribution region of the optimal well trajectory. Thus, in wellbore trajectory design within shale formations, it is crucial to determine the orientation of bedding and adjust the well trajectory accordingly to enhance wellbore stability. Furthermore, shale hydration does not impact the optimal well trajectory for a block, but with prolonged hydration, the minimum drilling fluid density required to maintain wellbore stability gradually increases. This suggests that hydration intensifies the weakening effect on bedding plane strength. The research results are helpful to understand the effect of hydration on shale wellbore stability and ensure shale wellbore stability during drilling cycle.

Hydration kinetics and apparent activation energy of cement pastes containing high silica fume content at lower curing temperature

To promote the application of silica fume (SF) in civil engineering in cold regions, relative influences from SF content and low temperature environment on the early hydration kinetics of composite cement pastes were evaluated based on the isothermal calorimetric method. The effect of high SF content on the apparent activation energy (Ea) of Portland cement and the filler effect (via the index of area multiplier) of SF on the hydration parameters was also analyzed. The results showed that the intensity of the shoulder peak (Al peak) of the hydration kinetic curve (heat flow curve) gradually grew as the SF content increased, and the double-peak phenomenon was gradually clear. The heat flow peak is delayed and lowered with the decreasing curing temperature, while the final time of the induction stage and the duration of the acceleration stage are delayed. Moreover, the duration of the acceleration stage was slightly extended with the increase of SF content. The full-width at half-maximum (FWHM) value of the heat flow curves dropped as the SF content and curing temperature increased. The low temperature environment and the inclusion of SF inhibited the growth in early hydration degree. The higher SF content mitigated the impact of low temperature on the hydration time parameter τ. The apparent Ea results also indicated that the SF reduced the temperature sensitivity of the hydration process of the composite cement pastes, which might contribute to the development of the hydration reaction at low temperatures. The AM (Area Multiplier) factor increased approximately linearly with increasing SF replacement levels. Apparent Ea decreased linearly with increasing AM, which may be attributed to a further reduction in the diffusion-controlled hydration rate of composite cement pastes with larger AM.